The subject matter of this disclosure relates generally to one or more of plane-wave creation, anechoic chambers, spatial channel models, and over-the-air testing of wireless devices.
Anechoic chambers have been used for decades to evaluate antennas and wireless devices in a controlled environment. Channel models have been designed for use with test equipment to emulate real-world fading conditions in controlled environments. Typically the channel models are implemented in the anechoic chamber using a ring of test-equipment antennas that surround the device under test (DUT). In particular, channel emulators feed the test-equipment antennas to create the desired fading environment at the location of the DUT, which is sometimes referred to as the “test zone.”
In the real world environment the DUT is rarely if ever located close to transmitters. Consequently, the field at the location of the DUT can be approximated well by a collection of propagating plane waves. Standard channel models prescribe that the field in the tests zone consist of propagating plane waves coming from specific directions. In order to achieve such a field in an anechoic chamber the distance between the test zone and the test-equipment antennas may have to be several wavelengths. As a consequence, the anechoic chamber is a large and expensive structure that may measure several meters across.